Vitamin B12 deficiency in a vegan diet: causes, symptoms and solutions

The Vitamin B complex consists of various vitamins, each with its own sources and distinct impacts on the body. In this blog post, we focus on the topic of vitamin B12 deficiency in vegans.

B vitamins are plentiful in fruits such as bananas. They are extremely important for our well-being and health, as they can positively influence our immune system and physical recovery. A varied diet that includes ample B vitamins is highly advisable to maintain these benefits.

However, vitamins like Vitamin B12 are often overlooked in a vegan lifestyle, which can lead to deficiency symptoms. So, what exactly is Vitamin B12 and what are its properties?

Key Facts About Vitamin B12

Vitamin B12 stands out in comparison to other vitamins, primarily due to its unique production and sources. While most vitamins are found in fruits, vegetables, or animal products, Vitamin B12 is generated mainly by bacteria, algae, and other microorganisms.

Maintaining an adequate level of Vitamin B12 is crucial for health, since this vitamin is a key factor in producing red blood cells and developing nerve cells. For the body to absorb Vitamin B12, it needs the protein known as the Intrinsic Factor, which is mainly produced in the stomach. A Vitamin B12 deficiency is relatively common and should be actively prevented because of its importance for blood formation and the nervous system.

Sources and Absorption

Vegans are at higher risk of a Vitamin B12 deficiency, given that the primary sources of this vitamin are often animal-based. A deficiency can reduce the production of red blood cells, and existing nerve damage might be treated or alleviated with adequate Vitamin B12 levels.

Hence, it is especially important for vegans to ensure sufficient Vitamin B12 intake—whether through fortified foods or supplements—to avoid health complications. The frequently recommended daily intake of Vitamin B12 is about 2 µg per day, and most of it is stored in the liver.^[1]

Do Vegans Automatically Have Deficiencies?

Vegans do face a higher risk of vitamin B12 deficiency if their intake is not carefully managed. To ensure adequate intake, it is vital to include B12-rich sources and, in many cases, take Vitamin B12 supplements. Some natural vegan sources of B12 are algae and kombucha.

Vitamin B12 (cobalamin) is essential for DNA synthesis and neurological functionality. A deficiency can lead to numerous hematological and neuropsychiatric conditions, which can often be reversed or improved if diagnosed early and treated promptly.

The exact prevalence of Vitamin B12 deficiency among the general population is difficult to determine. However, the incidence appears to rise with age. Medical studies have found that about 15 percent of adults over age 65 present a laboratory-confirmed B12 deficiency. Widespread use of acid-blocking medication can also lower B12 levels, potentially contributing to underdiagnosed deficiencies, especially in older adults.^[3]

Study and Daily Requirements

The bar chart below shows Vitamin B12 intake by age group for women (orange) and men (blue) in Germany, based on the National Nutrition Survey II (Nationale Verzehrsstudie II) from the Max Rubner Institute (2013). It reveals that women consume significantly less Vitamin B12 compared to men.

According to the D-A-CH reference values, adults aged 25 to < 51 years are advised to consume 4.0 µg Vitamin B12 per day. Pregnant women need 4.5 µg/day and lactating women require 5.5 µg/day.

It is therefore evident that women in Germany, in particular, often fail to meet these D-A-CH reference values for Vitamin B12 intake. This indicates that B12 deficiency is not only a problem among vegans but is also relatively common in the broader population. The D-A-CH reference values for nutrient intake are published by the German Nutrition Society (DGE), in collaboration with Austrian and Swiss nutrition societies.

A Vitamin B12 deficiency can go unnoticed for years, as the body holds large B12 reserves. Early indicators often include anemia. A deficiency can also lead to hair loss, memory problems, depression, and other symptoms.

Prolonged inadequate intake or poor absorption can cause a deficiency. Excessive consumption or loss of Vitamin B12 can further lower the body’s B12 level, and certain medications may exacerbate it.

How Does a Deficiency Manifest?

Vitamin B12 deficiency can cause exhaustion, weight loss, and may even contribute to dementia. Factors include the inability to split B12 from dietary proteins, poor absorption, and inadequate storage. Some drug-food interactions can also produce malabsorption and disrupt metabolism.

The significance of low B12, elevated homocysteine, and high methylmalonic acid levels in various diseases is still under investigation. Early screening and adequate supplementation of Vitamin B12 can help avert many associated disorders.

Vitamin B12 (cobalamin) deficiency is a common cause of anemia and is linked to a spectrum of neuropsychiatric disorders. Its role in hyperhomocysteinemia and atherosclerosis is still being researched. For vegans, it is especially important to ensure good sources of B12, possibly supported by supplements.^[4]

Conclusion

A Vitamin B12 deficiency is indeed frequently found in vegans and can lead to health complications. However, studies show that B12 deficiency is not limited to vegans. Even those who regularly consume meat can develop a deficiency. Vegans must consciously ensure sufficient Vitamin B12 intake—through foods like algae or kombucha, or more reliably via supplementation.

References

• [1] Mihaela Aluas, Vibrational studies of B6 vitamin, Vibrational Spectroscopy, 1999
• Irfana Hassan, Bhagwan Das, Santosh Kumar, Ghulam Haider Khalid, Abdul Manan Junejo, Noor-Un-Nisa, Rahul Kumar, Vitamin B12 Deficiency, The Professional Medical Journal
• [2] Adiga GU, Norkus EP Vitamin B12 deficiency. Recognizing subtle symptoms in older adults. Dharmarajan, EP, Geriatrics, 01 Mar 2003, 58(3):30-4, 37-8
• [3] Roman Pawlak, Scott James Parrott, Sudha Raj, Diana Cullum-Dugan, Debbie Lucus Author Notes, Nutrition Reviews, Volume 71, Issue 2, 1 February 2013, Pages 110–117
• [4] Robert OH, CPT, MC, USA, and David L. Brown, MAJ, MC, “How prevalent is vitamin B12 deficiency among vegetarians?”, Am Fam Physician, 2003